1999 Ls400 And Obd2

[B.Crosbie]

Hello,

We have a 1999 LS400 which has a few electrical gremlins. I found an OBD2 port under the dash and was thinking of getting an OBD2 cable and software for a laptop. Is the 99 fully OBD2 compliant and would a simple cable and cd tester be able to give any real information?

Regards,

Brandon

[landar]

A laptop with good scan software installed would show a lot of info...more than typical handhelds. But will probably cost you close to $200. A 99 LS400 is supported with this kit -> http://www.autotap.com/

I am not endorsing this package, just using as an example.

[B.Crosbie]

Budget won't stretch that far right now I'm afraid.

Just bought the car. Its an 1999 LS 400 (Right hand drive) and the battery was out of the car when I went to see it. I am experiencing the following problems and wondered if there might be a common fault;

Battery running flat overnight (charging at 13.5 v at low revs with lights etc on and nothing left on overnight.)

The temp gauge does not work despite the instrument clusted (dash panal) and the engine sender being replaced.

Lights for gearshift on instrument clusted not lighting (bulbs ok). Lights on shifter itself working.

Others not working;;

Outside temp gauge

Tilt steering. Was working but after some on and off of the negative battery terminal it too failed! It does work when the ignition is on but not when the key is put in initially like it should.

Cruise

Mirrors

CD

Trunk

Seat belt adjuster not working on drivers side

Power windows cannot be operated from drivers door panal except for drivers side. Lock switch does not function. All windows work from location!

Passangers seatback and height

Central locking (Key itself is functioning)

Brake wear light flashing (brake pads good, fluid ok, disconnecting fluid sensor changes nothing)

Heater makes a lot of noise

Changed all relays and all fuses are ok on both boards.

I understand that all of the above may not be linked but any help would be welcome.

Starts, drives and runs well.

[landar]

Lots of issues. If the car starts, drives and runs well, an OBDII is not going to find the inoperative circuits. You will need to get a schematic and volt/ohmmeter to start sniffing out the supply to each fuse and circuit. I would place the battery at the top of the suspect list as we really do not know its condition and often, when left to go dead several times, they will never again operate correctly. Do you have a battery in another vehicle that you could swap out to verify its not the battery?

[B.Crosbie]

Thanks for the replys landar. If the battery is able to start the car and keep it running under normal conditions then the battery could be ruled out couldn't it?

The problem arises when the car is left sitting overnight with nothing left on, the battery is drained the next day. We did some testing on the alternator and at idle the voltage input to the battery is about 14.5 volts. However under full load the voltage drops to around 12.3 volts but never goes below 12 volts. This is not correct obviously but could alternator trouble or battery trouble really cause all the problems listed above.

[landar]

You have the right thinking on this Brandon. In general, I would say 'yes, the battery is good' if the battery will start the car. The reason I mention the battery is that sometimes, I only get part of the story from posters. And you have so many electrical issues that the battery is the first to come to mind. It really sounds like you have a parasitic drain that is draining the battery overnight. The 14.5VDC and 12.3VDC (with loads) sounds about right. If you disconnect the battery cable overnight and then reinstall in the morning, does it start? If so, you will need to find what is drawing current when sitting.

Now, you mentioned checking fuses but you have to do a thorough job with this. Do not rely solely on sight. I have had bad fuses which look good. An ohmmeter tells a different story. And I would check for voltage right at the fuse box itself. I have a suspicion that the fuse box circuits may not be fed due to a broken wire or fusible link. Bad connector even. So get a voltmeter and start checking for voltage on each fuse. It might be missing which will get you tracing the line.

[B.Crosbie]

What is the current draw supposed to be when the car is fully "asleep"? We have gotten it down to 280mA, but that is still a bit high isn't it?

[landar]

Well, to be perfectly honest, I do not know exactly what it should be but I believe it should be lower than 50ma. How much lower, I don't know(it could vary as different circuits shut down). And be careful how you measure it. The ECU might take hours to go into quiescent mode so you cannot just shut down the engine, pull the cable and measure. I would let it setup with ammeter overnight and monitor in the morning. But yes, 280ma is too high. Check for an interior light being left on and perhaps not an obvious one (trunk, vanity mirror, etc).

[KeyKeeper]

70mA or lower. Pull the fuses till you find the one that drops it. Dont be surprised when you pull the ECM fuse and it drops sharply only to rise up to 700mA when reinserted. The caps in the ECM have to charge up and then the draw should drop back down below 70mA. My GS draws 38mA with nothing on. Battery goes dead after a week of not running. I have narrowed it down to a defective battery. Sounds like you have a ton of fuses either missing or blown.

[B.Crosbie]

Hi guys,

So after swapping the body cpu from another ls400 lots of the things that weren't working came back so obviously the body ecu was to blame.

However after putting the body ecu and any other components back into their original car the hazard lights have started working permanently on the donor car. Nothing we do apart from disconnecting the battery will turn them off which is annoying because apart from a couple of blown bulbs in the dash, electronically the donor car was perfect. My dad read somewhere that touching the two leads for the battery off each other whilst NOT connected to the battery would clear any codes in the ecus.

Could this have caused the problem or has something else happened because the ecus were moved between cars?

In addition to this we are trying to establish the model version of the donor car I have been refering too. It is a 1999 car which has satnav and according to the previous owner the more powerful interference engine (if cambelt breaks, pistons/valves get damaged). He also said it was a Mk3 which is contrary to what other people have said on forums such as this. According to them the Mk3 did not have satnav and a few other toys. We have 3 cars in total, 2 of which I suspect are Mk3 and one a Mk4. Is there any surefire way to tell them apart?

The suspected Mk4 has a flashing ECT light on the dash which was there when we bought it. It is also a bit jerky when changing in/out of park/reverse/drive. The ect button works fine and it will go into Power and Snow modes. After some reading we have found the main causes to be shift solenoids or error codes in the ecu. Is this diagnosis correct?

We are trying to decide which car is most worthwhile putting back on the road. The two main contenders have alot going for them but have niggly issues so if the ECT light turned out to be an easy enough fix then the suspected Mk4 would probably go back into service.

Regards,

Brandon.

[B.Crosbie]

Update: The hazards came on in the car we originally had electronic problems with regardless of the ecus which were in it. The hazards did not come on in the donor car in the same way until the ecus were swapped and then re installed in their respective cars.

With this in mind does that mean some error has been carried over between the two cars due to the ecus being swapped.

Regards,

Brandon

[fabphil]

I got also a leaking battery and I suspect the Body Ecu.

I think that the best way to get rid of these malfunctions is to spend much time with the electrical documentation, or to be lucky, but this doc is not that easy to deal with. There is also a diagnostic manual that you can find here http://www.ls400.ru/lexus-89-2000/ ?

[curiousB]

A couple comments to add to the story.

Battery current drain (called key off current drain) should be well under
100mA and probably under 50mA. The issue is when to measure it. Many of the car
circuits stay powered up for several minutes after shutting car off. Also
opening a door or hood can restart the delay sequence. Lastly an open hood can
also defer ECU from dropping into lowest power state.

So I would suggest connecting your Ammeter in series with the battery. Close
all doors. No key in ignition. Spoof the hood switch to think it is closed and
then wait half an hour to take a measurement. That is likely the true key off
current and the one you want to see quite low.

Now if it doesn’t measure well under 100mA try popping out fuses one at a
time to localize the rogue current drain. Be patient. Each time to open a door
you likely reset the power down sequence so need to wait to take a new measurement.

Lastly power drain can be due to a failing alternator. The stator diode
array can become leaky and when that occurs it becomes a current drain on the
battery that is not behind a fuse or a switch. Simple check for this is to
disconnect the charge line of the alternator and see if key off current drain noticeably
drops.

Happy sleuthing. These electrical problems can be tricky and subtle. Be
patient. Just try one variable at a time and move step by step.

[fabphil]

Yes I have checked the line from the battery going to the alternator, and I measured the current through a 22ohm resistance waiting the tension to stabilize.

Yes, you are right, this is a king of thing which needs patience. Meanwhile I just disconnect the battery and I have a spare battery in the trunk !

[Steve Chambers]

Though this may be posted elsewhere, I wanted to inform people who may not know of a neat way to read OBD-II info using an android device - I have a Google Nexus 7 tablet - with a Bluetooth OBD-II Wireless Transceiver Dongle and a $4.95 Android app called Torque Pro. It gives you realtime readouts of various functions while driving or idling, and error codes etc if you have any. I use it on my 1998 LS400.

Go to play.google.com (the Google app store) and search for Torque Pro to find the program.

I got the bluetooth device (ELM327 Bluetooth OBD-II Wireless Transceiver Dongle) from Meritline for $16.99. It's a cheap dongle, but seems to work well.

[landar]

Good info...thanks Steve! Much appreciated.